LIGHT OJ 1370 欧拉函数（在小于自身的正整数中有n个与自身互素的数，这样的数最小的为n后第一个素数）

#include<cstdio>
#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
const ll INF = -100000000000ll;
const double eps = 1e-8;
const int maxn = 1e6 + 10;
const double PI = acos(-1);
int pre[maxn];
void init(){
    pre[1] = 1;
    for(int i = 2;i <= 1000005;i++)
        if(!pre[i]){
            for(int j = i*2;j <= 1000005;j += i)
                pre[j] = 1;
        }

}
int main()
{
  //  freopen("in.txt","r",stdin);
    init();
    int T,cas = 0;
    cin>>T;
    while(T--){
        int n,a;
        cas++;
        scanf("%d",&n);
        ll ans = 0;
        for(int i = 1;i <= n;i++){
            scanf("%d",&a);
            a++;
            while(pre[a]) a++;
           // cout<<i<<" "<<a<<endl;
            ans += a;
        }

        printf("Case %d: %lld Xukha
",cas,ans);
    }

    return 0;
}